SI Units & Fundamental Quantities — MH-CET Physics MCQs with Solutions
Free MH-CET Physics SI Units & Fundamental Quantities MCQs with step-by-step solutions (21 questions). Part of Units and Measurements (Std 11). Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — SI Units & Fundamental Quantities · easy · theory
The number of fundamental quantities in the SI system is:
A. Three
B. Five
C. Nine
D. Seven ✓ Correct
Solution: They are length, mass, time, electric current, temperature, amount of substance and luminous intensity.
Q2 — SI Units & Fundamental Quantities · easy · theory
The SI base unit of amount of substance is the:
A. Kilogram
B. Candela
C. Mole ✓ Correct
D. Kelvin
Solution: One mole contains as many elementary entities as there are atoms in $12\text{ g}$ of carbon-12.
Q3 — SI Units & Fundamental Quantities · easy · theory
The SI base unit of luminous intensity is the:
A. Candela ✓ Correct
B. Lumen
C. Watt
D. Lux
Solution: Lumen and lux are derived units of luminous flux and illuminance respectively.
Q4 — SI Units & Fundamental Quantities · easy · theory
The SI base unit of thermodynamic temperature is the:
A. Degree Fahrenheit
B. Degree Celsius
C. Kelvin ✓ Correct
D. Joule
Solution: The kelvin is an absolute scale with its zero at absolute zero.
Q5 — SI Units & Fundamental Quantities · medium · theory
The radian and the steradian are classified in the SI system as:
A. Fundamental units
B. Derived units of mass
C. Practical units of length
D. Supplementary units ✓ Correct
Solution: They measure plane angle and solid angle respectively, and both are dimensionless.
Q6 — SI Units & Fundamental Quantities · easy · theory
A derived unit is one that:
A. Has no dimensions
B. Is expressed as a combination of fundamental units ✓ Correct
C. Cannot be expressed in terms of other units
D. Is used only in astronomy
Solution: The newton, for example, is $\text{kg}\cdot\text{m}\cdot\text{s}^{-2}$.
Q7 — SI Units & Fundamental Quantities · medium · theory
An advantage of the SI system over earlier systems is that it is:
A. Restricted to mechanical quantities only
B. Based on the imperial standards
C. Coherent and decimal, so conversions need no arbitrary factors ✓ Correct
D. Different in every country
Solution: Multiplying or dividing base units gives derived units directly, with no extra numerical constants.
Q8 — SI Units & Fundamental Quantities · easy · theory
The SI base unit of electric current is the:
A. Ampere ✓ Correct
B. Ohm
C. Coulomb
D. Volt
Solution: The coulomb is a derived unit, being one ampere second.
Q9 — SI Units & Fundamental Quantities · easy · numerical
The SI unit of force expressed in base units is:
A. $\text{kg}\cdot\text{m}\cdot\text{s}^{-1}$
B. $\text{kg}\cdot\text{m}^{-1}\cdot\text{s}^{-2}$
C. $\text{kg}\cdot\text{m}\cdot\text{s}^{-2}$ ✓ Correct
D. $\text{kg}\cdot\text{m}^2\cdot\text{s}^{-2}$
Solution: From $F = ma$, the newton is $\text{kg}\cdot\text{m}\cdot\text{s}^{-2}$.
Q10 — SI Units & Fundamental Quantities · medium · numerical
The SI unit of work expressed in base units is:
A. $\text{kg}\cdot\text{m}^2\cdot\text{s}^{-3}$
B. $\text{kg}\cdot\text{m}^{-1}\cdot\text{s}^{-2}$
C. $\text{kg}\cdot\text{m}\cdot\text{s}^{-2}$
D. $\text{kg}\cdot\text{m}^2\cdot\text{s}^{-2}$ ✓ Correct
Solution: The joule is a newton metre, that is $\text{kg}\cdot\text{m}^2\cdot\text{s}^{-2}$.
Q11 — SI Units & Fundamental Quantities · medium · numerical
The SI unit of power expressed in base units is:
A. $\text{kg}\cdot\text{m}^{-1}\cdot\text{s}^{-3}$
B. $\text{kg}\cdot\text{m}^2\cdot\text{s}^{-3}$ ✓ Correct
C. $\text{kg}\cdot\text{m}^2\cdot\text{s}^{-2}$
D. $\text{kg}\cdot\text{m}\cdot\text{s}^{-3}$
Solution: The watt is a joule per second.
Q12 — SI Units & Fundamental Quantities · medium · numerical
The SI unit of pressure expressed in base units is:
A. $\text{kg}\cdot\text{m}^{-2}\cdot\text{s}^{-1}$
B. $\text{kg}\cdot\text{m}^2\cdot\text{s}^{-2}$
C. $\text{kg}\cdot\text{m}^{-1}\cdot\text{s}^{-2}$ ✓ Correct
D. $\text{kg}\cdot\text{m}\cdot\text{s}^{-2}$
Solution: The pascal is a newton per square metre.
Q13 — SI Units & Fundamental Quantities · medium · numerical
One light year is approximately:
A. $3.08 \times 10^{16}\text{ m}$
B. $9.46 \times 10^{12}\text{ m}$
C. $9.46 \times 10^{15}\text{ m}$ ✓ Correct
D. $1.496 \times 10^{11}\text{ m}$
Solution: It is the distance light travels in one year: $3 \times 10^8 \times 365 \times 24 \times 3600\text{ m}$.
Q14 — SI Units & Fundamental Quantities · easy · numerical
One angstrom is equal to:
A. $10^{-6}\text{ m}$
B. $10^{-15}\text{ m}$
C. $10^{-10}\text{ m}$ ✓ Correct
D. $10^{-12}\text{ m}$
Solution: It is a convenient unit for atomic dimensions and for the wavelength of X-rays.
Q15 — SI Units & Fundamental Quantities · medium · numerical
One astronomical unit is approximately:
A. $1.496 \times 10^{8}\text{ m}$
B. $1.496 \times 10^{11}\text{ m}$ ✓ Correct
C. $9.46 \times 10^{15}\text{ m}$
D. $3.08 \times 10^{16}\text{ m}$
Solution: It is the mean distance from the Earth to the Sun.
Q16 — SI Units & Fundamental Quantities · hard · numerical
One parsec is approximately:
A. $3.08 \times 10^{12}\text{ m}$
B. $1.496 \times 10^{11}\text{ m}$
C. $3.08 \times 10^{16}\text{ m}$ ✓ Correct
D. $9.46 \times 10^{15}\text{ m}$
Solution: One parsec is about $3.26$ light years.
Q17 — SI Units & Fundamental Quantities · easy · numerical
One micron is equal to:
A. $10^{-6}\text{ m}$ ✓ Correct
B. $10^{-3}\text{ m}$
C. $10^{-10}\text{ m}$
D. $10^{-9}\text{ m}$
Solution: It is another name for the micrometre.
Q18 — SI Units & Fundamental Quantities · easy · numerical
A speed of $72\text{ km/h}$ expressed in metre per second is:
A. $36\text{ m/s}$
B. $18\text{ m/s}$
C. $20\text{ m/s}$ ✓ Correct
D. $25\text{ m/s}$
Solution: $72 \times \dfrac{1000}{3600} = 20\text{ m/s}$.
Q19 — SI Units & Fundamental Quantities · medium · numerical
One atomic mass unit is approximately:
A. $9.1 \times 10^{-31}\text{ kg}$
B. $1.6 \times 10^{-19}\text{ kg}$
C. $1.66 \times 10^{-27}\text{ kg}$ ✓ Correct
D. $1.66 \times 10^{-24}\text{ kg}$
Solution: It is one-twelfth of the mass of a carbon-12 atom.
Q20 — SI Units & Fundamental Quantities · hard · numerical
A density of $5\text{ g/cm}^3$ expressed in SI units is:
A. $0.005\text{ kg/m}^3$
B. $5\text{ kg/m}^3$
C. $5000\text{ kg/m}^3$ ✓ Correct
D. $50\text{ kg/m}^3$
Solution: $5\dfrac{\text{g}}{\text{cm}^3} = 5 \times \dfrac{10^{-3}\text{ kg}}{10^{-6}\text{ m}^3} = 5000\text{ kg/m}^3$.
Q21 — SI Units & Fundamental Quantities · medium · numerical
One newton expressed in dyne is:
A. $10^5\text{ dyne}$ ✓ Correct
B. $10^7\text{ dyne}$
C. $10^{-5}\text{ dyne}$
D. $10^3\text{ dyne}$
Solution: $1\text{ N} = 1\text{ kg}\cdot\text{m/s}^2 = 10^3\text{ g} \times 10^2\text{ cm/s}^2 = 10^5\text{ dyne}$.